The general goal of these investigations is to elucidate mechanisms of solute transport in the membranes of liver mitochondria and the relationships between these mechanisms and processes of cellular metabolism. Specifically some investigations are focusing on the energy-linked uptake of inorganic cations by mitochondria. The kinetics of unidirectional cation influx is being examined in relation to a proposed non-electrogenic transport mechanism. Some experiments are testing effects of inhibitors of oxidative phosphorylation in order to evaluate the extent to which the mechanism(s) of respiration-dependent cation influx may be directly linked to the mechanism of energy transduction. Other experiments are examinig the mechanism by which the urea cycle intermediate, ornithine, enters liver mitochondria.